Since running MT 3.2, I haven’t seen too many differences, except …
Well, MT-Blacklist is gone, which is (a) pointing out to me the tremendous amount of trackback spam I get (since I can view those Junked listings easily), and (b) giving me a way to deal with it by tossing anything dubious into moderation. Since 3.2 has gone up, no Bad Trackbacks have gone up. Huzzah. Makes me feel better if I can’t get to the page for a few days.
The other thing I’ve noticed: the Multiple Categories process for a post is much easier. Rather than pulling up a separate window, it simply pulls up a (Java?) set of check boxes that are very easily updated with but a single “save” at the end for the entire post. That’s a huge quality of life improvement for when you do category shuffling (as I’ve been doing a bit of lately).
The actual upgrade was much cleaner and straightforward an installation process than previous iterations; it still requires knowing how to do FTP and granting permissions to files and stuff like that, but it’s a lot cleaner and more professional than before.
Overall — well worth the effort of the upgrade, just for the two items listed, aside from the interface improvements.